1. Field of the Invention
The present invention relates to a microcrystalline silicon-containing silicon carbide (SiC) film preferably employed in an amorphous solar cell or the like, and a method of forming same.
2. Description of the Prior Art
Conventionally silicon carbide (SiC) film has been formed by a high frequency plasma CVD method.
The SiC film employed in an amorphous solar cell is required to have such properties as a wide optical energy gap and a high dark electric conductivity.
However, the above described conventional SiC film is low in both of the above described properties. And even by doping the conventional SiC film was boron for improving the above described properties, the resulting dark electric conductivity is only about 10.sup.-5 through 10.sup.-8 Scm.sup.-1 at the optical energy gap Eg of about 2.0 eV.
And it is well known that the optical energy gap Eg can be increased by increasing the carbon content in the SiC film. However, as the carbon content is increased, the dark electric conductivity is rapidly decreased. For example, the dark electric conductivity at the optical energy gap of 2.1 eV is as small as 10.sup.-6 through 10.sup.-9 Scm.sup.-1.
In the case in which a p-type amorphous (SiC(a-SiC) film formed by the conventional method is employed in a window layer (p layer) of a p-i-n type amorphous silicon solar cell, problems arise in that photo-electric current generated in an i layer due to the solar radiation cannot be effectively delivered to an external electrode because of low dark electric conductivity, and that solar radiation entering the solar cell is absorbed by the p layer because of the narrow optical energy gap thereof so as not to effectively reach an electricity generating layer (i layer)